You are reading Part 5 of 9 in this series.What are Quick Facts?
Evidence continues to mount that human-induced climate change is causing hurricanes to grow stronger and more destructive. Hurricanes are producing heavier rain, their storm surges are riding atop higher sea levels, and in many cases they are lingering longer over land, causing increased flooding and infrastructure destruction.
Facts for Any Story
Tropical cyclones, which include hurricanes, have been by far the costliest and deadliest kind of weather or climate disaster in the United States since 1980, costing over $1.3 trillion and causing nearly 7,000 deaths.1NOAA Billion-Dollar Weather and Climate Disasters: Summary Stats, 2023 View Source As of the summer of 2023, the five costliest U.S. Earth-system disasters (including earthquakes, volcanic eruptions, fires, and all kinds of extreme weather, adjusted for inflation) since 1980 have all been hurricanes, and all five have occurred within the past 20 years: Katrina (2005), Harvey (2017), Ian (2022), Maria (2017), and Sandy (2012).2NOAA Billion-Dollar Weather and Climate Disasters: Events, 2023 View Source
Globally, recent decades have seen a disproportionate increase in especially strong hurricanes, which pose the greatest threat to lives and property. Scientists compared hurricane intensities from 1979 to 1998 and again from 1999 to 2017 and found a statistically significant increase in the fraction of hurricanes in categories 3, 4 and 5 (those with the highest wind speeds) during the second of those two 18-year periods. The observed trends are consistent with those projected by models of hurricane activity in a warming world.3Kossin, James P. et al., (2020), Global increase in major tropical cyclone exceedance probability over the past four decades, PNAS, 117 (22) 11975-11980 View Source
Hurricanes get their energy from ocean heat; the warmer the water is, the stronger a hurricane can get. More than 90% of the excess heat trapped in the climate system due to human-caused global warming has gone into the oceans, providing the added energy driving recent hurricanes’ extreme wind intensities and the increased evaporation that has resulted in associated torrential rainfall.4IPCC, 2014, Synthesis Report, Summary for Policymakers, p. 4. View Source
Both heavy rain and storm surge—water pushed ashore by heavy winds—contribute to flooding, which causes the vast majority of hurricane-related deaths and financial losses. The amount of rain falling in some recent hurricanes was substantially increased due to human-caused climate change,5Reed, Kevin A., et al., (2022), Attribution of 2020 hurricane season extreme rainfall to human-induced climate change, Nature Communications, 13 1902 View Source including in Harvey (by 20 to 38%),6Risser, M. D., et al., (2017), Attributable human-induced changes in the likelihood and magnitude of the observed extreme precipitation during hurricane Harvey, Geophys. Res. Lett., 44, 12457–12464 View Source7Wang et al., Quantitative attribution of climate effects on Hurricane Harvey’s extreme rainfall in Texas, Env. Res. Lett., 13, 054014. View Source Ian (18%),8Reed, K. and Wehner, M., (2023), Real-time attribution of the influence of climate change on extreme weather events: A storyline case study of Hurricane Ian rainfall, Environmental Research: Climate, 2 043001. View Source Katrina, Irma, and Maria.9Patricola, C. and Wehner, M., (2018), Anthropogenic influences on major tropical cyclone events, Nature, 563, 339–346. View Source Modeling suggests this increase in precipitation led to a 14% to 18% larger area flooded in greater Houston during Harvey, and one study estimated that the cost of flooding attributable to human-caused warming alone was $13 billion.10Wehner, Michael and Christopher Sampson (2021), Attributable human-induced changes in the magnitude of flooding in the Houston, Texas region during Hurricane Harvey, Climatic Change, 166 (20) View Source Hurricanes are also producing higher storm surges due to sea level rise.9Patricola, C. and Wehner, M., (2018), Anthropogenic influences on major tropical cyclone events, Nature, 563, 339–346. View Source
Analysis of Hurricane Harvey’s damages in Harris County, Texas, estimates that around one-third to one-half of the flooded properties would not have flooded without human-caused climate change, and that low-income Hispanic or Latino households were disproportionately affected.11Smiley, Kevin T. et al., (2022), Social inequalities in climate change-attributed impacts of Hurricane Harvey, Nature Communications 13 3418 View Source
Climate-change-related perturbations in atmospheric winds like the jet stream appear to be contributing to a trend in which hurricanes are moving more slowly over the United States12Rahmstorf, S., (2017), Rising hazard of storm-surge flooding, PNAS, 114 (45), 11806-11808 View Source (slowing by 17% over the past century),13Kossin, J. P., (2019), Matters Arising, Reply to Moon et al. and Lanzante, J.R.. Nature, 570, E16-E22. View Source and are increasingly likely to “stall” near the coast, potentially leading to catastrophic local rainfall and flooding.14Hall, T. M. and Kossin, J. P., (2019), Hurricane stalling along the North American coast and implications for rainfall, Climate and Atmospheric Science. View Source15Zhang, Gan, (2020), Tropical cyclone motion in a changing climate, Science Advances, 6:17. View Source
There has been a significant increase in how quickly hurricanes intensify in the Atlantic basin in recent decades, an expected symptom of global warming.16Bhatia et al., (2019), Recent increases in tropical cyclone intensification rates, Nature Communications, 10, 635. View Source In fact, hurricanes in the Atlantic affecting the U.S. East Coast are now more than twice as likely to rapidly intensify from a weak storm to a Category 3 or greater storm than they were in the 1970s and ‘80s.17Garner, Andra J. (2023), Observed increases in North Atlantic tropical cyclone peak intensification rates, Scientific Reports, 13 16299. View Source Hurricanes that intensify rapidly are difficult to forecast accurately and prepare for, especially when this occurs close to the coast, and cause a disproportionate amount of human and financial losses.18Emanuel, K., (2017), Will global warming make hurricane forecasting more difficult?, Bulletin of the American Meteorological Society, 98, 495-501. View Source
On average, the development of the first named hurricane in the Atlantic now occurs about a month-and-a-half earlier than it did 40 years ago, with most of that due to increasing warmth of Atlantic waters.19Truchelut, Ryan E. et al., (2022), Earlier onset of North Atlantic hurricane season with warming oceans, Nature Communications, 13 4646. View Source
Globally, hurricanes are reaching their maximum intensities further from the tropics, shifting toward temperate, heavily populated coastal regions that have not historically experienced them. Northern Hemisphere hurricane peak intensities have shifted northward by 100 miles in the past 30 years.20Kossin, J. P., et al., (2014), The poleward migration of the location of tropical cyclone maximum intensity. Nature, 509, 349-352. View Source
Recent projections suggest that the U.S. Southeast and Gulf Coasts will face increased hurricane risk due to the effects of continued global warming on steering currents and wind shear.21Balaguru, Karthik, et al., (2023), Increased U.S. coastal hurricane risk under climate change. Science Advances, vol. 9 issue 14. View Source
Pitfalls to Avoid
Avoid asking whether climate change “caused” a particular hurricane to slow, intensify rapidly, etc., as there are always many contributors to any weather event. Instead, ask whether climate change contributed to the intensity of a hurricane or the likelihood of its especially damaging behavior (such as stalling over a coastline)—questions that scientists can increasingly answer with confidence given recent advances in attribution science.
Dr. James Kossin
National Oceanic and Atmospheric Administration, National Centers for Environmental Information